1. Field of the Invention
The present invention relates to a lubricant and a magnetic recording medium using the same. More specifically, the lubricant allows for low friction, low abrasion sliding between two touching solids, regardless of high or low speeds, or high or low loads, and under all environmental conditions such as high or low temperatures, or high or low humidity. The present invention also pertains to the use of this lubricant in magnetic recording media having excellent durability and traveling performance.
2. Prior Art
With the aim of allowing for low friction, low abrasion sliding between two touching solids and lengthening the usage period of instruments and equipment, development is being carried out on the hardening of solid surfaces and on lubricants. The demand for size reduction in the OA instrument field is particularly strong, and every year precise mechanisms in the slidable portion area are introduced. In the future, precision parts will require increasing reductions in friction and abrasion when the sliding begins, ends and is in progress, and a greater reduction in the load on the motor, etc., than is provided by the current slidable instruments, when they operate continuously or discontinuously under a broad range of environmental conditions. In conventional protective lubrication systems, the slidable position has a hard surface layer which is difficult to abrade, and grease, oil, half-solid or liquid lubricants are used.
However, in precision equipment in which smoothing of the touching portions have been completed, a lubricant which allows low friction, low abrasion sliding between two touching solids regardless of high or low speeds, and high or low loads cannot be obtained. Thus, the problems of poor starting, or a sudden accidental increase in the friction force when sliding cannot be avoided.
When compared to coating type magnetic recording media, ferromagnetic metal thin film type magnetic recording media, which are made by depositing ferromagnetic metals or their alloys, etc. on a non-magnetic support by vacuum deposition, etc., can easily increase the anti-magnetization properties and decrease the thickness of the media, and have good high-density recording properties. On the other hand, they have disadvantages in that the coefficient of friction at the magnetic head increases, and they are easily abraded or damaged, since they use no tough binder resin, and the ferromagnetic metal thin film layer or the protective membrane has good surface smoothness. Thus, their durability and traveling performance are inferior.
Accordingly, durability and traveling performance are improved by the provision of various lubricants, such as ester-type lubricants, on the ferromagnetic metal thin film (see U.S. Pat. Nos. 4,735,848, 5,356,726 and 5,376,465, and Japanese Kokai Patent Publication Nos. 60-85427, 2-210615, 4-368621 and 6-274858).
However, the problem of smudging on the magnetic head or "drop out" has not been solved. The durability and traveling performance are insufficient, especially under high temperature and humidity conditions.